Ecosystem services in the Yangtze River Economic Belt: Spatiotemporal characteristics, trade-offs/synergies, and driving factors

Ecosystem services (ES) play a vital role in socioeconomic development. Existing research has primarily focused on single-service assessments and linear relationships, overlooking often neglecting non-linear interactions, threshold effects, and spatial heterogeneity among ES. The Yangtze River Economic Belt (YREB) was analyzed to evaluate water yield (WY), soil conservation (SC), carbon storage (CS), habitat quality (HQ), and total ecosystem services (TES). Methods including constraint lines, geographically weighted regression, and machine learning were applied to systematically identify spatiotemporal evolution patterns, interrelationships, and driving factors of ES. The results indicate that (1) from 2005 to 2020, ES in the YREB exhibited marked spatiotemporal variability. WY and SC increased over time, whereas CS, HQ, and TES declined. Spatially, SC, CS, and HQ were consistently higher in western and southern regions, while WY followed a southeast-to-northwest decreasing gradient. (2) Relationships between ES revealed distinct dynamics: CS-HQ, WY-CS, and SC-CS were dominated by trade-offs, whereas WY-SC, WY-HQ, and SC-HQ displayed synergies with constraint effects, demonstrating pronounced spatial heterogeneity. (3) Annual precipitation above 0.25 and Normalized Difference Vegetation Index values exceeding 0.46 significantly enhanced positive drivers of TES. Built-up area proportions greater than 0.49 reversed from negative to positive effects. The Nighttime Light index and the proportion of built-up areas emerged as the primary negative drivers. These findings provide a scientific basis for ecological conservation strategies and regional sustainable development, advancing comprehensive assessment and management of ecosystem services.